Anycast DNS and Unicast DNS: Contrasts & Comparison

Let’s examine the differences between Anycast DNS and Unicast DNS!

Anycast DNS

Anycast DNS involves multiple name servers that are positioned in different locations all over the world. All of them store and are able to provide the same IP address. Anycast DNS routes the users’ DNS requests to the nearest and available server. 

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Unicast DNS

Unicast DNS includes just one name server holding the IP address and all of the DNS data (DNS records) of your domain name. That means all of the DNS requests are routed to this specific name server. Additionally, the location of the user does not matter because only this single server can provide the needed DNS information.


Anycast DNS and Unicast DNS have one major contrast.

Anycast DNS: The DNS resolver responsible for obtaining the DNS data for the requested hostname is configurated with one Anycast IP address for a particular group of name servers. That reduces the latency, and there are no delays because of non-responsive name servers. In addition, thanks to Anycast DNS, Points of Presence (PoPs) that are unreachable are automatically excluded, and the DNS resolver is directed to the closest best performing DNS server.

Unicast DNS: The DNS resolver could request the needed DNS data from a lot of different DNS name servers. It usually asks one of them and waits for its response, or there is a timeout. Only then the resolver proceeds and asks the second server. Therefore, that has the potential to create high latency. 

Anycast DNS and Unicast DNS: Comparison

Let’s compare Anycast DNS and Unicast DNS based on several criteria and factors. That way, you can easily understand which one is the preferred choice for you, and it is going to fit your needs.

Simple to implement: Using and installing Unicast could be easier due to the fact it involves one machine and one IP address. Yet, the incorporation of Anycast DNS is also not so difficult. In addition, with Unicast DNS, you are required to maintain an individual server. On the other hand, configuring several servers with Anycast DNS means a little bit more effort.

Safety and Security: It tends to be a little bit more risky to hold just one server with all of the DNS data (DNS records). If it crashes or it is under attack, you could experience losses. All of your clients are not going to be able to reach your website, which affects in a negative way your reputation and finances. When you implement Anycast DNS, you have multiple servers that can answer users’ requests. That means even if one of them crashes, the others will still be able to handle the incoming traffic.

Response time: If your visitors are waiting too much for a response, it won’t be a surprise if they leave your website. Even without exploring your website content! On the other hand, Anycast DNS acts quickly and significantly improves the response time.

Target market: Unicast DNS is a great choice, and it is going to fit perfectly anyone that offers services and products in a local market. Yet, if you want your business to grow, or you are operating already on a multinational level, then you should choose Anycast DNS.

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